Transport device and method



United States Patent 3,495,821 TRANSPORT DEVICE AND METHOD Donald E.Raterman, Mount Prospect, Ill., assignor to Addressograph-MultigraphCorporation, Mount Prospect, III., a corporation of Delaware Filed May10, 1968, Ser. No. 728,108

Int. Cl. B65h 5/06 US. Cl. 271-51 5 Claims ABSTRACT OF THE DISCLOSURE Asimaged sheets exit from the fixing section of electrostatic copyingequipment, they must be engaged and forwarded into the receiver, andthis occurs normally before the image, comprised of a thermoplasticresin, is fully set. In order to prevent tracking of the resin image bythe rollers which feed the sheet out, there is provided one or moreporous rollers which are impregnated with silicone oil and which are theonly members in contact with the imaged surface of the sheet at thispoint.

BACKGROUND OF THE INVENTION This invention relates to the delivery ofcopies, especially from electrostatic copying machines, and is addressedto the problem of tracking which sometimes arises when the thermoplasticresinous image is not fully set as the sheet encounters the pull-outrollers which take it from the usual fixing station and place it in thereceiver. If the image is still soft or semi-liquid, a portion of theimage material may be picked up on the surface of the feed-out rollersand transferred therefrom to background portions of the same sheet orother sheets where no image is desired.

It will be recognized that in certain respects the problem is associatedwith the speed of machine operation. At low operational speeds thefusing can be accomplished at lower heat levels since the thermoplasticresinous material comprising the image is permitted a longer time in theheating station to come up to its fusing temperature. As the speed ofthe machine is increased, the temperature of the heating station must beincreased in order to compensate for the decreased time the copy sheetspends under the influence of heat. At the greater speeds, and henceincreased heat levels, the image tends to remain in a softened conditionafter it leaves the fusing station at the time the rollers move intocontact with the image so that offset will occur. On the other hand, ifsome means could be devised for preventing the offset in a simple andeconomical way, the speed and output of the machine need not be limitedin this respect and substantial increases could, in many cases, beeffected.

Heretofore the image sheet has been fed from the fixing station by meansof lightly contacting, relatively impositive feed rollers whereinnon-opposed frictional tire portions arranged in staggered relationshipdeflect the sheet in a slightly wavy configuration, and thereby use theresilience of the sheet to maintain a delicate driving contact with thetires. This arrangement has proved quite satisfactory, but, as the speedof the equipment is increased and also the heat levels, it has beenfound that even this light contact is sufiicient to cause some track ingbecause of the softer condition of the image when it reaches the rollersand the higher temperature of the rollers.

It will be recognized, of course, that it is important for accuratepaper handling to have the rollers as close to the fixing section aspossible so as to maintain control over the sheet. When, as is commonlythe case,. the fixing station is of the heat fusing type, this proximityresults in an elevated temperature of the rollers which tends tomaintain any imaging material which they pick up in a softened conditionfor ready transfer to surfaces where 1t 18 unwanted.

It would, moreover, be beneficial if the rollers could engage the sheetin a more positive manner to insure a uniform motion through and out ofthe fixing section of the copier. This is especially the case where heatfusing is used and where, if the sheet overstays its time in the fixer,there is a possibility of charting.

BRIEF DESCRIPTION OF INVENTION According to the present invention, avery simple and exceedingly effective solution to these problems hasbeen discovered. The pull-out rollers are arranged to engage the sheetin a light pressure nip to provide a rather positive feed, and theroller or rollers engaging that surface of the sheet which carries theimage are of a porous character and impregnated with silicone oil. Ithas been found that virtually no image material is picked up by theimpregnated rollers, although the image may still be soft and tacky whenit encounters them, and consequently the speed of operation of the wholemachine can be substantially increased.

DESCRIPTION OF THE DRAWINGS The embodiments of this invention have beenillustrated diagrammatically in the accompanying drawings, but it is tobe expressly understood that said drawings are for purposes ofillustration only and are not to be taken as a definition of the limitsof the invention, reference being had to the appended claims for thispurpose. In the drawings,

FIGURE 1 is a diagrammatic side elevation of a portion of anelectrostatic copier illustrating the invention;

FIGURE 2 is an elevation to a larger scale of the pull-out rollers takensubstantially on line 2-2 of FIGURE 1;

FIGURE 3 is an enlarged detail perspective illustrating the improvedroller of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring to the drawing, thefusing section of the copying machine is indicated at 11, and includes aheating element 13 energized by a source 15 of electrical energy, areflector 17, and a conveyor 19 upon which the sheets of paper S arecarried past the heating apparatus, image face up.

The pull-out roller assembly is designated 21 and comprises a pair offixed side members 23, 23 which provide rotatable mounting for a lowerroller 25, and an upper roller 27, the latter made up of a shaft 29carrying two sheet contact cylinders 31. The cylinders 31 are arrangedfor light contact with the surface of roller 25 and form therewith a nipto receive and positively move forward a sheet introduced between them.Suitable means (not shown) of a conventional nature are provided fordriving the rollers 23 and 25 at the surface speed of sheets S as theyissue from the fuser section 11. The rollers 25 and 27 cooperate toforward the sheets S in turn to the receiver 33.

As previously indicated, the cylinders 31 are of porous material of anyof various sorts. Materials which are substantially rigid have beenfound to be most suitable for the present application. One which hasbeen found particularly useful is powdered bronze, sintered andcompressed to form a porous metal body similar to that used in themanufacture of self-lubricating bearings. It will be understood,however, that any porous body of suitable metallic or plastic materialcan be used for this purpose.

The porous body is then impregnated with a liquid that prevents theadhesion of the softened resin to the surface of the cylinder. Theliquid in the cylinder comes to the Feb. 17, 1970 D. E. RATERMAN3,495,821

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